For half of the 20th century, the task of surveilling New Zealanders to root out spies, dissidents or enemy sympathisers lay with the police force.
They were there during pre-war industrial action at the mines, tracking down men called to fight in World War One, at Depression-era protests and monitoring foreigners during World War Two.
Large numbers of people were swept up in the surveillance net - most of them law abiding citizens. Authors Richard Hill and Steven Loveridge have pieced together how the state security apparatus worked, and the people and institutions that were seen as actual or potential threats to its interests.
Their book Secret History: State Surveillance in New Zealand 1900 - 1956 is the first of two volumes.
Photo: Supplied
